Definition

Noun: * An optical aberration resulting in a distorted image: A defect in lenses or mirrors with spherical surfaces where light rays from the outer edges (marginal rays) focus at a different point than light rays passing through the center (paraxial rays). This failure to converge at a single focal point causes a blurred or distorted image.

Usage

• Spherical aberration is a fundamental concept in optics and lens design.
• It is a key factor limiting the sharpness and resolution of simple optical systems.
• The term is used when discussing the quality and correction of lenses in cameras, telescopes, microscopes, and eyeglasses.

Examples

• The simple magnifying glass exhibits noticeable spherical aberration, especially at its edges.
• To reduce spherical aberration, high-quality camera lenses use aspherical elements.
• Astronomers must correct for spherical aberration in telescope mirrors to obtain clear images of celestial objects.
• The blur in the photograph was caused by lens spherical aberration, not by camera shake.

Advanced Usage

• Longitudinal Spherical Aberration (LSA): The axial distance between the focus of paraxial rays and the focus of marginal rays.
• Transverse Spherical Aberration (TSA): The radial height at which a marginal ray intersects the paraxial focal plane.
• "To correct for spherical aberration": A common phrase describing the design process of using multiple lens elements, aspheric surfaces, or mirror configurations to minimize this optical flaw.

Variants and Related Words

• Aberration (n): A departure from what is normal, usual, or expected, typically one that is unwelcome. In optics, it refers specifically to imperfections in image formation.
• Chromatic Aberration (n): An optical defect where a lens fails to focus all colors (wavelengths) to the same convergence point, resulting in color fringing.
• Aspheric Lens (n): A lens with a non-spherical surface profile, often designed specifically to reduce spherical aberration.

Synonyms

• Optical distortion (in a general sense)
• Lens defect
• Focus error

Related Concepts (Not Phrasal Verbs or Idioms)

• Paraxial Ray: A light ray that travels close to the optical axis.
• Marginal Ray: A light ray that passes through the edge of the aperture.
• Focal Point: The point where light rays converge.
• Point Spread Function (PSF): A mathematical description of how an optical system images a point source, directly affected by spherical aberration.

Noun

1. an optical aberration resulting in a distorted image